The present invention involves the ejection of ink drops by way of forming gas or vapor bubbles in a bubble forming liquid. This principle is generally described in U.S. Pat. No. 3,747,120 (Stemme). Each pixel in the printed image is derived ink drops ejected from one or more ink nozzles. In recent years, inkjet printing has become increasing popular primarily due to its inexpensive and versatile nature. Many different aspects and techniques for inkjet printing are described in detail in the above cross referenced documents.
Nozzle packing density, or the number of nozzles per square mm of printhead, has a bearing on the print resolution and fabrication costs. In view of this, there are ongoing efforts to increase nozzle packing densities. As a result, individual nozzle structures are configured to reduce the spacing between adjacent nozzles. One such configuration uses an elongated ink chamber and similarly elongated ink ejection actuator to reduce the spacing between adjacent nozzles. However, ejecting a substantial proportion of the ink in an elongate chamber out of a nozzle involves significant hydraulic losses. To overcome these losses, the actuator uses more energy to create a pressure pulse in the ink that is sufficient to eject a drop. Therefore, the overall efficiency of the printhead is lower than an actuator in a less elongated chamber.